Non-woven and perforated textile fabrics made from continuous synthetic fiber, and a process for the manufacture of same

ABSTRACT

A perforated non-woven textile web is prepared from continuously extruded filaments. The filaments are formed into a web which has alternately arranged, continuous filaments of relatively linear portions which are physically cross linked at various portions along the filament lengths. The filaments also have finely folded portions along their length and the web also has projections and perforations in and on its surface. The web is arranged in such a manner that the filament and finely folded portions are entangled with each other at each of the projections to provide a reinforced latticework structure.

United States Patent [191 Tsurumi et al.

1 NON-WOVEN AND PERFORATED TEXTILE FABRICS MADE FROM CONTINUOUSSYNTHETIC FIBER, AND A PROCESS FOR THE MANUFACTURE OF SAME [75]Inventors: Takashi Tsurumi; Shuichi Emori;

Kiyokazu Daigoh; Takemi Ikegami; Tutomu Kaneko, all of Nobeoka, Japan[73] Assignee: Asahi Kasei Kogyo Kabushiki Kaisha, Osaka, Japan 221Filed: July 24, 1973 211 App]. No.: 382,217

[30] Foreign Application Priority Data July 25, 1972 Japan 47-74320 [52]US. Cl. 428/131; 428/296; 428/369 [51] Int. Cl. D04H 3/05; DO4H 3/14[58] Field of Search 161/47, 57, 58, 59, 70,

[56] References Cited UNITED STATES PATENTS 3,485,706 12/1969 Evans161/72 [4 1 Sept. 16, 1975 3,485,708 12/1969 Ballou et al 161/723,485,709 12/1969 Evans et a]. 161/109 3,498,874 3/1970 Evans et al.161/109 3,531,363 9/1970 Shambelan 161/57 X 3,537,945 ll/l97O Summers161/57 Primary Examiner-George F. Lesmes Assistant ExaminerAlan T.McDonald Attorney, Agent, or FirmArmstrong, Nikaido & Wegner ABSTRACT 2Claims, 20 Drawing Figures PATENTED T 51975 73, 8' 08,130

SHEET 1 UP 5 FIG, 3

(J/Cm) UNI M T RIAL M.

a 600 o/l 84 @400 FIG. 4

. I UNIT MATERIAL wt. 0 IO E AMPL'TUDE' IIII (mm) 4 YF/Yumox 3 NON-WOVENAND PERFORATED TEXTILE FABRICS MADE FROM CONTINUOUS SYNTHETIC FIBER, ANDA PROCESS FOR THE MANUFACTURE OF SAME This invention relates to improvednon-woven and perforated tex'tile fabries made from continuous syntheticfiber filaments, representing superior strength and hand touch and aprocess for the manufacture of same. Recently, non-woven textile fabricshave attracted large public attraction, since these modern type of textile products represent a grave future prospect. From this reason,textile manufacturers have performed vast and various developments andinvestigations on and into this kind of new type fabrics, regardless oftheir manufacturing origin of synthetic, regenerated or natural fibers,and miracle and charming products thereof have already appeared on themarket. These nonwoven textile products represent peculiar and Superiorrespective characteristicsv As an example, spun-bond products made fromsynthetic fibers have such characteristics as low cost and high tensilestrength and are highly suitable for use as industrial materials,interior decorative materials and the like, and they have alreadyacquired .public acceptance. On the other hand, the dry orwet-manufactured non-woven fabrics from rayon short fibers pulp fibersand the like have found their wide use as disposable materials, sanitarymateri als, wiping and the like materials.

,ln consideration of the aforementioned general situation of thenon-woven fabrics, it is the main object of the present'invention toprovide a substantially improved non-woven fabric having superiorstrength as well as hand touch and the like characteristics, especiallysuitable for useas the disposable material for sanitary, wiping,clothing and the like purposes.

A further object of the present invention is to provide a suitableprocess for the preparation of such improved non-woven fabric as above.I

It is highly desirable for the above kind of various purposes,especially for the sanitary fibrous material, to provide the followingperformances:

1. it must be prepared from a material having a superiormoisture-absorbing ability comparable to that of cellulose.

2. it must represent a high value of tensile strength which is notsubjected to appreciable reduction even when wetted.

3. it must not contain any harmful substance to human bodies, such asoiling, glueing and/or the like agent.

4. it does not contain liably separating-off short length fibers andthus, it should preferably be prepared from continuous filaments.

5. it must be manufactured at low cost.

According to our knowledge, such non-woven fabrics as satisfying all theaforementioned superior characteristics have not yet been realized. Asan example, although certain kind of the synthetic fibermade spun bondnon-woven fabrics may have the several favorable characteristics, asmentioned above at items 2 5, those prepared from the material havingsuperior moistureabsorbing performance comparable to that of celluloseas mentioned at the above first item 1 have not yet been realized.Conversely, the non-woven fabrics prepared either in the wet or drymanufacturing process by the use of rayon staples, cotton fibers or thelike may satisfy the above first item 1, those desirous characteristicsmentioned at the above items 2, 3 and 4 can not be satisfied.

A still further and more specific object of the present invention is toprovide a remarkable non-woven fabric capable of representing all theaforementioned characteristics at item 1 5, and a process for themanufacture of same.

The non-woven fabric according to this invention represents thefollowing features:

1. it is manufactured from highly favorable moistureabsorbing fibrousmaterial as obtainable by the wet-spinning process of cuprammoniumrayon, viscose rayon and the like fibers.

2. it is composed of continuous filaments and capable of beingmanufactured by the process which is directly combined with the spinningprocess.

3. the filaments are intimately and strongly interwound with each otherwithout use of bonding agent, providing nevertheless high values ofdryand wet tensile strength. it is composed of a number of continuousfilaments having relatively linear parts which are physicallycross-linked with each other, so as to represent generally a multipleand composite latticework, said filaments being formed into a web whichrepresents an infinite number of projections distributed geometricallyover the whole surface of the web and the filaments being united witheach other at these projections and by such filament portions as havinga high degree of freedom so as to provide high values of dryand wettensile strength of the web.

5. the provision of the aforementioned projections provides anappreciable bulkiness and a soft hand touch.

6. the non-woven web represents a substantially geometrically arrangedperforations and the filaments are bonded together at a number of pointssubstantially in the point-contact manner, thereby representingbilateral flexibility.

The process according to this invention for the manufacture of the abovementioned novel non-woven web may be carried out in the followingmanner.

1. Spinning liquor is extruded from a large number of spinning orificesarranged generally in a rectangular or elongated ellipse, into acoagulation liquid bath and the extruded filaments are led to flowdownwardly together with the bath liquid for coagulation andregeneration and the thus coagulated filaments are led out from anoutlet opening having an elongated slit and opening at the lower end ofthe coagulation bath, together with the bath liquid, and then thefilaments are caused to make freedropping under the influence of gravityforce and in such state that the filaments groups is totally envelopedby the outgoing and down-flowing coagulation bath liquid curtain.

2. More than three spinning units of the above kind are so arranged inseries with each other at a predetermined mutual distance in thedirection of travel of a pervious conveyor and above the latter that themajor axis of each of the rectangular hexahederal spinning part of theunit crosses, when observed from above thereof, at tight angles to theconveyor arranged directly below the spinning units at a certainpredetermined vertical distance therefrom and laterally thereto.

3. The pervious conveyor while it advances at a certain predeterminedtravel speed is caused to oscillate laterally and generally so that thecast-on continuous filaments from each of the spinning units describerespective and parallel sinusoidal curves thereon. In this case, all thesinusoidal curves from the spinning units are overlapped one filament/-group after another filament group and at a predetermined off-phaserelationship by arranging the spinning units in the corresponding seriesway relative to the conveyor.

4. When the impinging velocity of the filaments against the travellingconveyor is assumed to be V the travelling velocity of the conveyor tobe I) and the lateral oscillation velocity of the conveyor as measuredat the origin of the oscillation to be v (it becoming maximum by theresultant of V with the lateral velocity) and by varying V and v or byvarying the lateral oscillating velocity, the following relation isestablished:

1 F/ N mar 5 for at least three spinning units; and

for at least one spinning units.

5. At a downstream point from the filament impinging points, the thusformed filament web on the same conveyor or upon transferred therefromonto a further and different conveyor is showered directly with liquidjets and from directly above the filament web.

In this way, a non-woven filament web having the aforementioned uniquecharacteristics can be manufactured in a successful way.

In the following, the invention will be described more in detail byreference to the accompanying drawings, in which:

FIG. 1 at 1a and 1b represents in a modelized form the conventionaldepositing manner of continuous filaments on a travelling conveyor asspun according to the wet funnel spinning process and to the syntheticfiber spun-bond process, respectively.

FIG. 2 at 2a, 2b and represents in modelized forms, several filamentsinterwinding modes when realized by three, four and six continuousfilaments as funnel-spun and impinged on a travelling and at the sametime laterally oscillating pervious conveyor, respectively.

FIG. 3 is a chart showing the longitudinal tensile strength of the webas spun and impinged on a longitudinal travelling and laterallyoscillating conveyor as obtainable with variation of the conveyoroscillation amplitude.

FIG. 4 is a chart showing a ratio of tensile strengths,

as measured longitudinally and laterally of the web when the oscillationamplitude is set to a constant while the ratio of: oscillation amplitudeto half wave length is varied.

FIG. 5 is a schematic view illustrative of several suc cessive steps ofthe manufacturing process according to this invention.

FIG. 6 is a schematic plan view of a mechanism employable in the presentinvention for subjecting the travelling pervious conveyor to a lateraloscillation movement.

FIG. 7 at a, b and 0 show several modes of combined curve arrangementperformed by one and four continuous filaments on a longitudinallytravelling and laterally oscillating conveyor and a web structure, by alarge number of filaments, having been illustrated in highly modelizedforms.

FIG. 8 at a and b are schematically illustrating views for theexplanation of a web-perforation step employed in the process accordingto the present invention, the web structure being shown at a before thestep and b after the step, respectively, for easy comparison.

FIG. 9 is a schematic perspective view of an elongated rectangularspinning unit employable in the process according to this invention.

FIG. 10 is a schematic cross-section of the spinning unit shown in FIG.9.

FIG. 11 is a representation of a microscopic photograph of a part of theupper of front surface of a non woven web prepared by the processaccording to this invention.

FIG. 12 is a similar view to FIG. 11, illustrative of part of the rearsurface of the same web.

FIG. 13 is a schematic enlarged plan view of the nonwoven fabricaccording to this invention.

FIG. 14 is a sectional view taken substantially along a section line A Ashown in FIG. 13.

When a filament is deposited from a funnel spinning unit onto atravelling pervious conveyor and when the filament velocity is higherthan the conveyor speed, it is fixedly cast thereto as shown at a ofFIG. I. In this figure, three parallel filaments are shown in parallelfor easy comparison. The lateral amplitude is highly irregular andrather limited.

In the case of the filament prepared by the spun-bond process, thefilaments can be deposited on the conveyor in a still highly irregularmanner, showing a high variety of lateral deviation. The differencebetween the both shown at a and b, respectively in FIG. 1 may beattributed to the difference in the kind of the medium employed, or morespecifically, the liquid in the former and the gaseous medium in thelatter.

In the case of the spun-bond process, the cast-on filaments cross witheach other over a relatively wide area and the resulted filamentsstructure may represent a high tensile strength advantageously. In thecase of the web spinning process, the filaments may normally be cast onthe conveyor, each in a rather elongated and zig-zag shape with rathersmaller lateral deviation, thus providing a rather weak structure of thefibrous web. As an example, when each of the filaments is taken outlongitudinally from the web structure, it can normally be easily drawnout. In order to avoid such disadvantageous phenomenon by setting thedifference between the filament velocity and the conveyor travellingvelocity to a smaller possible value, the filaments could be cast on intheir nearly linear arrangement on the pervious conveyor. In such case,although the longitudinal tensile strength will become extremely high,the lateral strength may be only smallest.

On the other hand, we have found according to our profound experimentsthat when the non-woven web formed by the wet-spun continuous filamentsof cuprammonium-, viscose rayon and acrylonitrile and cast-on onto awire net similarly as in the aforementioned way, is showered from upperwith liquid jets, a

meshedly perforated product can easily be provided. This means such thefilaments parts lying on the wires are flushed hydraulically down intothe mesh openings of the wire-or gauze net. Therefore, such portions ofthe previously formed fibrous web which correspond to the wires aresubjected to formation of the perforations, while those of the web whichhave been flushed into the gauze openings will form downwardlyprojecting projections from the common plane of the web.

According to our practical experiments with the ratio: V /v broadlyvaried, it has been found that with the ratio set to higher than 3,there is a remarkable tendency to invite neat and rather sharply definedformation of the perforations of the above kind. The spray nozzles whichhave been used by us in these perforating experiments were of the flattype having a spraying angle of 40. The outlet pressure was set to 5kg/cm with a water delivery rate of 5 lit./min. From this, it has beenconcluded that for hydraulic rearrangement of the web structure, theconstituting filaments must have certain degree of freedom. It wasfurther found, however, that the perforated non-woven web thus preparedrepresents only small longitudinal and lateral tensile strengths and is,therefore, far from its acceptable con dition.

In the progress of our experiments in the above sense, such a thoughthas been hinted that a perforated nonwoven web of high strength may berealized combiningly cast-on of rather linearly arranged filaments partswith rather finely zig-zag-shaped and folded filaments parts at aproperly selected ratio and the thus formed web is then subjected to theaction of water jet streams. In the thus provided and hydraulicallyperforated web, the rather linearly arranged filaments parts willprovide a skelton-like structure and the rather high freedom filamentsparts will entangle the skelton, and thus, the resulted perforated webmay represent high tensile strengths in the longitudinal and lateraldirections of the web.

When the conveyor is caused to laterally oscillate by means of a camorcrank mechanism, as an example, while the conveyor is advancing at acertain constant speed of v the overall motion thereof can be expressionby the following mathematical equations:

x v n z (the distance x has been taken in the conveyor-advancingdirection) y a sin 2'rr nt (the distance has been taken in the lateraldirection) Then, the respective velocities will be:

v,,=21r'a'n'cos2rrnl where,

n represents the lateral oscillation cycles/min of the conveyor;

a stands for the amplitude of the oscillation;

I represents /2 wave length of the oscillation;

t represents time in minutes.

The resultant velocity V of the longitudinal and lat eral velocities ofthe conveyor will be:

V 11 411 11 11 cos 277!!! Therefore, the conveyor velocity V as measuredat the original point of reciprocation will become:

and it will be at the peak or valley:

N min N Then, the ratio of filament velocity relative to conveyorvelocity will be always:

Therefore, at the peak or valley, the filament will represent a moreaccumulation than that appearing at the origin of the reciprocatingmotion by such factor as:

Now assuming V /V l, the value of V Iv will vary as shown in thefollowing Table, with variation of a/ 1.

0.2 L18 04 L61 0.6 2.13 0.8 2.70 1.0 3.30 [.2 3.90 1.4 4.5 l 1.6 512 2.06.36

As it is well supposed from the foregoing analysis and as ascertained byour practical experiments, when a number of filaments are spun by thewet spinning process and impinged by gravity action upon the conveyorwhich is caused to advance at a constant velocity and subjected tolateral oscillation at the same time, a fibrous non-woven web composedof relatively linearly arranged filaments portions and those which haverelatively high degree of freedom, and further that when the thus formedweb is subjected to hydraulically perforating action of the kindreferred to specifically hereinbefore, an acceptably perforated webproduct having high longitudinal tensile strength could be realized, aswill become more apparent as the description proceeds.

In the spinning stage as an initial step of the process according tothis invention, the continuous filaments are arranged in an evenlydistributed state enveloped within a liquid curtain and caused to emergeout from an elongated slit-like outlet in such distributed and envelopedstate.

At the spinning step, at least three spinning units are employed, thereason therefor residing in the attainment of uniformity in the webappearance as well as web strength. If bearable with somewhat inferioruniformity in the above sense, only two wet spinning units may beutilized within the framework of the present invention. i

In FIG. 2 at a, b and c, yarn wave configurations attainable with use of3, 4 and 6 spinning units are shown. It is most preferable, thesinusoidal wave curves represent each phase lag of 21r/n, when n standsfor the number of wet spinning units employed. It should be understoodin these diagrams that the wave pattern diagram is shown only in ahighly simplified way that each filaments array consisting of, say,90,000 filaments delivered from each spinning unit is shown only asingle line.

The amplitude and frequency of the lateral oscillation given to thepervious conveyor means can be varied within a broad range so as toprovide attractive products. However, it should be stressed at thisstage that there are the following general principles in this respect: a

A. Amplitude ,a. I

With the ratio of a/ 1 fixed and with variation of a, the strength ofthe web will vary as shown representatively in FIG. 3. We have obtainednon-woven fabrics of sufficient strength .by selecting the value of awithin the range of 50mm.

B. Number of oscillations.

When the conveyor is caused to travel at a constant travelling velocity,the pitch of the sinusoidal curve of the filament will be varied byvariation of the number of oscillations per unit time.

With the value of a a fixed and with variation of the pitch, a relationas representatively shown in FIG. 4, can be obtained. As seen from FIG.4, a web having longitudinal and lateral strengths well balanced witheach other may be produced when the ratio all is set to about 0.5. Thedifference between the longitudinal and lateral tensile strength of theweb will become more appreciable, depending upon the degree of deviationof the saidratio from 0.5. Within the framework of the presentinvention, the value of 11/1 may be varied within a vast range,depending upon the usage of the final products.

When a number of spinning units are employed, at least three setsthereof should represent the value of ratio: V /V set to l '5. This isfrom such reason that by the adoption of this measure, the formation ofthe skeleton of filaments can thereby be assured. With higher value ofthis ratio than 5, the web can not procombinations thereof will be shownhcreinbelow for better understanding of the invention.

1. Three spinning units were employed. V 30 m/min.

11 8 rn/min. (1/1 I.

In this embodiment, each of all the spinning units represents F N max 51.1 V s/U E 3 8 2. Use of four spinning units.

For three units, W 30 m/min. v 15 m/min. a/l

For the remaining one unit, V 60 m/min.

Then, for the three units:

For the remaining one unit: V,-/v- 4 In the hydraulic perforation step,a punched metallic sheet or web may equally be used in place of theguaze wire net as the pervious conveyor for movingly carrying thefibrous non-woven web, with equal results. As the pervious conveyorarranged directly below the spinning units for casting-on of thecorresponding number of continuous filaments, we use preferably anendless plain-woven wire gauze net of 40 60 mesh. The caston continuousfilaments web can be as per se subjected to a hydraulic perforation jobby use of a plurality of liquid jets. Or alternatively, the fibrous webmay be transfered onto a further pervious conveyor for subjecting it toa hydraulic perforation job. In the latter case, a gauze wire net of 1060 mesh can be advantageously employed.

In place of the plain-woven wire net. any one or any combination ofthose of triple-woven, twill-woven or the like wire net may equally beused for attaining a correspondingly modified perforation design effectof the final products.

I In place of wire net, a perforated non-woven fabric web may also beused.

Most advantageous and preferable liquid medium adapted for the formationof liquid jet streams to be utilized for the execution of the hydraulicperforation job may be water. Its most suitable performance for thefiber rearrangement, easy operability and workability and its highesteconomy must be taken into account for carrying out the process of thepresent invention.

As the spray nozzles for use in the present process, various known typesmay be employed. Circular shower type nozzles and flat shower type onehave been used with better results.

The liquid pressure at the oulets of the jet nozzles depends upon theratios of V /v and V /V and upon the overallfeed rate of the continuousfilaments as spun and cast on. With higher values of V /v and V /V andwith smaller feed rate of the continuous filaments, the outlet liquidpressure will become smaller.

The thus prepared perforated non-woven fabric web of the presentinvention represent geometrically arranged perforations corresponding tothe nonperforated substance parts of the net or punched carrier web, anda large number of projections corresponding to the perforations oropenings of the carrier web and consisting of entanglements of therelated parts of the continuous filaments, and further, stringlikefilaments bundle parts connecting said projections with each other.

At each of said projections, high freedom filaments are intimatelyentangled with low freedom filaments arranged in a latticework skelton,so as to provide a wcllorganized overall structure of the non-woven web.

In the following, a plurality of processing steps of the manufacturingprocess of the present invention will be described hereinbelow in detailbe reference to FIG. 5.

In FIG. 5, numeral 1 represents an endless type wire net conveyor whichcirculates clockwise therein as shown by a small arrow and by beingmovably supported by rollers 2, 3, 4 and 5 of which those denoted 2; 3may be drive rollers receiving motion from a proper prime mover, notshown.

Above the net conveyor 1 and in proximity to the left-hand end thereof,there are provided a plurality of, herein three, spinning units,generally shown at A. At intermediate place between the both ends of theconveyor net 1 and directly thereabove, there are provided severalscouring units 33 35 consisting a scouring stage, generally shown at B.C represents a perforating stage and D a drying stage. The perforatingstage C" and the drying stage D are related with a further net conveyorwhich circulates along a number of rolls or cylinders 6 14, of whichthose denoted 11 14 constitute in combination a cylinder dryer machine.In fact, rollers 6; 7 are of the driving type and the cylinder rolls 1114 are driven from a suitable prime mover, not shown. In this way, thenet conveyor 15 can circulate in clockwise direction in FIG. 5, as shownby a small arrow.

Numeral 16 represents a machine frame carrying the constituent parts ofthe spinning and scouring stages A and B, said frame 16 being rigidlysupported on columns 17 19 which are connected pivotably to the upperparts of stationary pillars 23 25 rigidly supported on the base blocks22, respectively.

Roller 2 is rotatably mounted on top of a column 26 which is connectedat its lower end pivotably to the upper part of a stationary pillar 28rigidly supported on a base block 27.

In FIG. 6, roller 2 and frame 16 are mechanically connected to amechanical oscillator unit E. Numcral 29 represents an electric motor,while 30 denotes a casing in which a crank mechanism is contained,although not shown. As may be well supposed, actuation of the motor 29so as to bring the oscillator unit E into operation, will oscillate toand fro, roller 2, net conveyor 1 and frame 16 horizontally in FIG. 6 inuni- In FIG. 5, numeral 31 represents three spinning units 31, eachfunnel thereof having a horizontally elongated rectangular shape, as maybe well supposed from joint consideration of FIGS. 9 10. Each of thesespinning funnels has its major axis directing in the lateral directionrelative to the travelling net conveyor 1.

Numeral 32 represents a plurality of suction boxes arranged directlybelow the net conveyor and in vertical registration of spinning units31.

Numeral 33 35 represent trays arranged above the net conveyor 1 andadapted for supplying scouring liquor in showers towards the nextconveyor, said trays consituting representatively the scouring stageNumeral 36 represents a plurality of water jet nozzles arranged abovethe next net conveyor 15, so as to constitute the hydraulic perforationstage C" for the execution of the perforation job, as was referred tohereinbefore, by use of water jet streams directed onto the fibrous web.Suction boxes 37 are also provided, below the net conveyor 15 and invertical registration with the nozzle group 36. 38 represents a take-uproller pair for the cast-on and hydraulically perforated fibrous web and39 represents a wing-up roll for the latter.

Next, referring to FIGS. 9 and l0,'the details of the spinning unit 31will be described more in detail.

In FIGS. 9 l0, numeral 40 represents a spinning liquor supply pipe; 41an outer casing; 42 a nozzle plate formed with a large number ofspinning orifices, not shown, generally arranged in a horizontal plane,so as to represent an elongated rectangular or elliptical outlineconfiguration; 43 an upper funnel element defining an upper coagulationliquid bath; 44 a lower funnel element defining a lower coagulationliquid bath; 45 an intermediate separator wall; 46 a supply inlet forprimary coagulation bath liquid; 47 a supply inlet for sec ondarycoagulation bath liquid; 48 51 respective rectifier plates; 52 aslit-like outlet opening formed at the lowermost end of the lower stagecoagulation liquid bath.

In these figures, the spinning liquor is supplied through supply inlet40 and extruded through a number of extrusion orifices formed throughthe nozzle plate 42 in the downwardly vertical direction.

As for the extrusion orifices, each of the latter may have, as anexample, an orifice diameter of 0.8 mm. These orifices may have a mutualpitch of 1.5 mm and they may be arranged in rows when seen in thetravelling direction of the conveyor net 1, and in 1,000 rows in thelateral direction thereto, thus being 90,000 orifices in total per unit.

The bath liquid introduced into the upper bath 43 is led to flowdownwards therethrough and together with the extruded filaments from thenozzle orifices. As seen, the coagulation bath keeping its longer majoraxis unchanged in its length, will reduce, however, gradually in itslateral width, as the bath liquid flows down towards the bath outlet.Therefore, the bath liquid flow increases gradually its downflowingspeed.

The inlet temperature of the coagulation bath liquid is set to asuitable level so as to provide proper coagulation degree of theextruded continuous filaments by contact with the bath liquid accordingto the prior technique.

The filaments are then brought into contact with the secondarycoagulation bath liquid prevailing in the lower coagulation bath 44, soas to be further coagulated and stretched to a proper degree, and arriveat the slit-like outlet opening 52, thence therethrough discharged asbeing totally enveloped within a liquid curtain formed by the downwardlyoutgoing bath liquid.

This discharged liquid curtain from the slit outlet opening 52 will flowdownwards with its lateral length kept unchanged, in the form of aliquid film or sheet, containing therein a curtain-like consisting ofthus extruded, coagulated and stretched continuous filaments andrepresenting a substantially constant thickness. In FIG. 5, the thus andsimilarly formed three liquid curtains are shown in a highly simplifiedmanner by parallel vertical lines at 53.

These liquid curtains or sheets 53 containing therein a filamentscurtain-like core are led to drop without destructing the rectifiedcurtain flow through the free open air atmosphere under gravity actionand impinge against the upper surface of the travelling net conveyor 1.In a practical example of the cuprammonium rayon spinning process, thespinning units are arranged three in its number at a mutual distance of1 meter in the direction of the travel of the net conveyor 1.

As the net conveyor 1 advances, it is subjected to lateral oscillatingmovement, as was referred to in connection with FIG. 6. As an example,the conveyor 1 is driven to travel at a speed of m/min and laterallyshaked at 250 cycles per minute with an amplitude of mm.

As the dropping continuous filaments impinge against the upper surfaceof the longitudinally travelling and laterally oscillating net conveyor1, they are cast on the latter while describing an off-phasedly combinedsinusoidal curves, as was referred to hereinbefore in connection withFIG. 2 at (I). Upon execution of said impinge of the continuousfilaments enveloped by the liquid curtain, the liquid will be suckedinto by the respective suction boxes 32. For this operation, thefilament velocity, the conveyor travelling velocity and the conveyoroscillation frequency are properly adjusted, so as to set the values ofV /V and V /v within the reasonable range as set forth hereinbefore.

By adopting proper values of V /V and V /v and by selecting the numberof the spinning units at 3, 4 and 6, respectively, differently cast-onfilaments schemas as shown at (I), (II) and (III) in FIG. 2 will berealized for providing non-woven fibrous webs.

At the peaks and valleys of the sinusoidal curve, the filament is moredensely accumulatedly cast on the pervious carrier web 1 and theydeposit rather linearly along its transient portions between peaks andvalleys on the carrier web. It results in the formation of such webcomprising filaments portions generally forming a latticework skelton asshown in FIG. 7a and those representing finely and rather densely foldedfilaments portions, said both kinds portions being mixedly entangledwith each other to provide said non-woven web.

The thus formed web is carried away as cast-on onto the advancingconveyor and subjected to a scouring step. In the case of thecuprammonium spinning, a diluted sulfuric acid aqueous solution of5%acid concentration is delivered from the first tray 33 for thispurpose. Fresh and clean water is delivered from the succeeding trays34; 35 for the same purpose. In this way, the constituent filaments ofthe web have been regenerated and washed.

Upon thus water-cleaned, the web is transferred from first conveyor 1 tosecond conveyor 15 which carries it further. During this advancingmovement of the second conveyor, the web is subjected to a hydraulicperforating job, as was referred to hereinbefore.

During this step, water jet streams are injected from flat spray nozzles36 positioned directly above the second conveyor, as shown in FIG. 8a,against the travelling web. At the same time, the suction boxes 37 areoperated to suck water from below the second conveyor. In this figure,numeral 54 represents the web at this stage.

At this stage, the constituent filaments of the web is in its state thatthey are shiftable in their mutual position upon subjected to pressureliquid action. Therefore, the filaments are rearranged in their positionby receiving the influence of the liquid energy. The rearrangingoperation has been illustrated in FIG. 8b. Part of the web 54 shown inFIG. 8a has been shifted and has dropped into mesh openings of thecarrier web, the latter portions of the web being thereby high denselyenlarged together. In this case, even when parts of the latticeworkskelton may be shifted in the similar manner, however, the wholestructure of the skelton can not be destroyed. Thus, the liquid energymay serve to shift parts of the filament bundle skelton and toconcentrate them locally.

Destruction of the skelton will not occur if the water jet energy iscontrolled so as not to break the constituent filaments.

Those filaments parts of the web which are finely zigzag formed can betransferred in their position with relatively small amount of energy.The water jet energy is set to by consideration of such facts. Favorableresults were obtained in the case of cuprammonium nonwoven web, the jetwater delivery rate of 10 lit./min. and at the pressure of 20 kg/cm perspinning set, the nozzles being positioned at mm above the web.

The thus hydraulically perforated non-woven web represents a regulararrangement of elongated perforations and downwardly directingprojections, the latticework-maintaining filaments portions densely andintimately entangled with finely zig-zag shaped filaments portions.Therefore, it will be seen the basic latticework is maintained in itssubstance, but losing its original plan configuration and being bundledtogether.

The thus fabricated web, having regularly perforated and projected webis conveyed on the second carrier web through a hot roller type drierzone and finally wound up into a roll.

The non-woven fabric thus prepared naturally consists of a large numberof continuous filaments highly entangled together, yet preserving theoriginal rigid structure in its substance, thereby representing highvalues of longitudinal as well as lateral tensile strength comparativeto woven fabrics, and indeed, by preparing with no use of glueing agent.

Since the non-woven fabric web according to this invention represents aregular arrangement of a large number of small elongated perforationsand small downwardly directing projections and the very maintainance ofhighly entangled filaments entanglement without use of any specialadhering agent, the overall hand touch thereof is similar to sanitarygauze clotch and finds its vast and various usages as sanitary, wipingand disposable cloth materials.

The non-woven fabrics according to this invention can be prepared aswell by use of acrylonitrile filaments in place of those of cuprammoniumor viscose rayon.

EXAMPLE 1 Perforated non-woven fabric web was manufactured by use ofcuprammonium regenerated cellulose filaments in accordance with theprocessing step schematically shown in FIG. 5. Three wet spinning unitswere used, each being of the type shown schematically in FIGS. 9 and 10in its perspective outline and in its schematic elevational section,respectively. These units were arranged in series in the travellingdirection of the pervious carrier conveyor at a mutual distance of 1meter. water which Used cuprammonium cellulose spinning liquor preparedaccording to the common practice and having a composition of celluloseconcentration 10.0 wt.%; ammonium concentration 7.0 wt. and copperconcentration 3.6 wt. was extruded from a large number of 90 X 1,000extrusion orifices of the nozzle plate as at 42, FIG. 10, so as toperform the funnel spinning step. The bath liquid was deaerated softfresh which was fed to the bath funnels in two successive verticalstages in an overflowing in-flowing method. The orifices were of 0.8 mmbore and arranged in a rectangular matrix, the mutual pitch being 1.5mm.

The bath liquid consisting of deaerated fresh water was fed at the ratesof 100 lit./min. (34C) and 1 l lit./- min. (46C) for the two stagecoagulating baths, respectively.

In this way, the extruded fine spinning liquor streams were coagulatedand were discharged with the entraining bath liquid flow through theoutlet slit openings 5.0 mm wide, and in the form of the compositecurtain containing parallel-arranged sheet-like filaments core.

The composite curtain of a substantially constant thickness was causedto flow 500 mm downwards freely through an open atmosphere and toimpinge against at V 2 40 m/min at stainless steel wire gauze net (of400 mesh) advancing at a constant speed of m/min. The conveyor waslaterally oscillated forcibly at 125 cycles per minute with an amplitudeof mm. For each of the three spinning units, V /V was set to 2.2 and V/v to 4, respectively.

Upon the impinge of the composite curtain, the bath liquid on thecarrier conveyor was sucked through the mesh openings thereof byrespective suction boxes having slit-like suction openings arrangedoppositely to and similar opening dimensions of the correspondingspinning units.

The thus cast-on non-woven web was carried away by the travellingcarrier net and washed with aquious acid solution and fresh water asbeing conveyed, for the purpose of the regeneration as known per se andthen transferred onto a further stainless steel net conveyor of mesh.This transferred fibrous web was then subjected to a hydrous perforationjob by applying from upper water jet streams from a plurality spraynozzles of the flat type which are positioned at a distance of 150 mmabove this second conveyor net. The water supply jet for these spraynozzles was set to 10 lit/min per spinning unit and at a pressure of 20kglcm A similar suction box was provided below the net conveyor forsucking into the exhaust water upon carrying out the hydraulicperforation job and through the mesh openings of the conveyor and at asuction pressure of 74 mmHg which could be applied to the first suctionboxes cooperating with the spinning units.

As the second conveyor travel along, the thus perforated web was passedthrough a tunnel dryer for drying thereof to provide the final product.

The thus manufactured perforated non-woven fabric web had highlongitudinal and lateral strength similar to surgical cloths as well assuperior hand touch comparative to woven fabrics.

In the following Table l, tensile strengths and drape characteristic ofthe nonwoven fabric web thus obtained are shown.

Table 1 Drape* Wet Strength Characteristic Dry Strength* Lat. 11.8

Lat. 1 7.3

Long.

Long.

Magnified photographs a part of the non-woven perforated web are shownby the reproduction in FIGS. 11 and 12. FIG. 11 represents the front orupper surface taken with a magnifying factor 10, while FIG. 12 shows therear or lower surface of the same non-woven fabric taken with amagnifying factor 3.

EXAMPLE 2 In this example, four spinning units were used which werearranged in series in the travelling direction of the first carrier webat a mutual distance of l m. The spinning and the conveyor driveconditions were same as before. The number of lateral oscillations andconveyor advancing speed were so selected that the continuous filamentsgroups from these were cast on successively one after another at mutualoff-phase relationship of oscillation period.

The thus prepared basic web was transferred to a second carrier web orconveyor, of 28 mesh, stainless steel plain-woven net, and thensubjected to a hydraulic perforation job. Spray nozzles were of fiattype. The jet water was delivered at a rate of 5 lit./min, the deliverypressure being 13 kg/cm The characteristics of the thus prepared,perforated non-woven fabric were similar to those obtained in theforegoing example 1.

EXAMPLE 3 Six spinning units of the type same as before were used. Thefree dropping distance of the multifilaments for the first and fourthspinning units was set each to 700 mm. That for the second, third, fifthand sixth spinning units was set to 400 mm, respectively. The spinningspeed for the first case was 56 m/min and that for the second case was31 m/min.

The travelling speed of the carrier web was set to 15 m/min at lateraloscillations per minute with an amplitude of 20 mm.

V V mar 2.0 for the first and fourth units.

On the other hand, for the second, sixth units:

VF/VN mar 32 The thus cast-on web was transferred onto a second carrierweb, plain-woven stainless wire gauze net of 30 mesh, and subjected to ahydraulic perforation job as before. The spray nozzles were of flattype.

The water supply rate was 10 lit./min at 20 kglcm The dried webrepresented the following characteristic data.

third, fifth and Table 2 Dry Strength Wet Strength Drape bong. Lat.Long. Lat. Characteristic EXAMPLE 4 vided with 30 X 200 orifices, 0.1 mmbore, 1.5 mm pitch.

The thus formed composite curtain was led to impinge upon a conveyor notpositioned at 500 mm below said outlet and travelling at m/rnin whichconsists of a 40-mesh stainless steel wire net. V amounted to 26 m/min.The conveyor was oscillated at 50 cycles per minute with an amplitude of30 mm. V /V 24; V /U 5.2

The thus cast-on filaments web was transferred onto a second carrierweb, made of a 30-mesh stainless steel gauze wire net and then subjectedto a hydraulic perforation job as before. Water delivery rate waslit/min at 20 kg/cm The results were substantially same as before.

EXAMPLE 5 The coagulation bath liquid contained: 130 g/lit. of sulfuricacid; 300 g/lit. of sodium sulfate; and 20 g/lit. of zinc sulfate. Atthe first stage, the bath liquid was supplied at a rate of 100 lit./min(40C) and at the second stage, it was fed at equal rate (60C).

The thus extruded, coagulated and somewhat stretched continuousfilaments were delivered through each slit-like outlet of 2.0 mm widthand in a filament curtain enveloped within a downflowing bath liquidcurtain.

Acrylonitrile 94 wt. parts; acrylamide 5.5 wt. parts; acrylsulfonate 0.5wt. part; ammonium supersulfate 4 wt. parts and thiogrycol 0.2 wt. partwere dissolved in 1,000 wt. parts of water, adjusted pI-I3 with additionof a small amount of sulfuric acid and left at rest at 60C for 5 hours.The thus formed polymer was dissolved in 70%-nitric acid, 0C, so as toprepare a spinning liquor containing 12 wt. of the polymer.

With use of this spinning liquor, continuous filaments were extruded,coagulated, stretched and cast-on onto a travelling pervious conveyorwith use of the arrangement shown in FIG. 5. The spinning units weresame as used in the foregoing Example 1. However, the number of thespinning units was four in place of three. Each unit had an orificeplate having an array of 20 X 150 orifices, 1.0 mm bore diameter,arranged at pitches of 2 The coagulation bath liquid was a 37%-nitricacid aqueous solution. The inlet rate between first and sec ond bathstage was 1 1. Bath temperature was set to 3C for the both.

The width of the lower outlet opening amounted to 2.0 mm, and the netconveyor was positioned therebelow at a 300 mm-distance and driven totravel at 7 m/min. The conveyor was a 40-mesh stainless steel wire gauzenet.

V 27 m/min.

Lateral oscillation was at 75 cycles per minute with an amplitude of 20mm. For all the four units:

The thus cast-on filaments web was subjected to a hydraulic perforationjob with use of fiat type spray nozzles at water delivery rate of 6.4/min per spinning unit at a delivery pressure of 15 kg/cm The suctionboxes were operated at 740 mmHg. The filaments entanglement and mutualfixture were performed without use of any bonding agent.

The results were superior as before.

The general structure of the perforated non-woven web prepared accordingto this invention is shown schematically in FIGS. 13 and 14 in its planview and in its cross-section, respectively.

In these figures, numeral 101 represents regularly arranged elongatedperforations, while 102 represents downwardly extending projectionswhich are again regularly arranged. In the general aspect, when seenhorizontally in FIG. 13, perforations 101 and projections 102 arearranged alternatively with each other.

The projection 1022 represents a densely condensed and mutuallyentangled filament mass. As seen from FIG. 13, these projections 102 arelaterally (horizontally in FIG. 13) and longitudinally (vertically inFIG. 13) connected one after another by relatively thin band-likeconnecting portions 103. When horizontally seen, a pair of theprojections 102 define one end of said elongated perforation or opening101. When vertically seen, the next pair of the projections 102 definethe opposite end of the next succeeding perforation or opening 101.These four projections 102 are connected crosswise by two physicallycross-linking band portions 107. Vertically seen in FIG. 13, each twoprojections 102 are connected with each other by substantially parallelyseen filament strip 106. Two projections 102 are connected with eachother laterally by a substantially parallely seen filament strip 108.This strip 108 takes generally a convex curve when seen in FIG. 14. 105represents a yarn loops extending from each projection 102, providingfavorable chance of entanglement with similar yarn loops of a furthersimilar web when several similar webs are overlapped one after another,for providing any desired thick web group.

= The foregoing explanation relating FIGS. 13 and 14 concerns theappearance or visual apparent observation only. The true structure ofthe whole organization is based upon the uniquelatticework-andentanglement combination explained by reference to FIG. 2and the like as set forth hereinbefore.

The embodiment of the invention in which are exclusive property orprivilege is claimed are as follows:

1. A perforated non-woven textile web made from continuously extrudedfilaments produced by a wet spinning process, wherein the web consistsessentially of alternately arranged continuous filaments of relativelylinear portions (A) which are physically crosslinked to each otherwithout the use of bonding agents at various portions along the lengthof said filaments to form a latticework structure, said filaments alsohave finely folded portions (8), wherein the finely folded portions areevenly distributed over the entire area of the web, the web havingregularly arranged projections and perforations such that the filamentportions (A) and (B) are entangled with each other at each of theprojections to fix and reinforce the latticework structure, the webhaving an arrangement such that the web represents an infinite number ofprojections distributed geometrically over the whole surface of the weband the filaments being united with each other at these projeetions.

2. The web according to claim 1 wherein the projections and perforationsare alternately arranged in the lengthwise and laterwise directions ofthe web.

1. A PERFORATED NON-WOVEN TEXTILE WEB MADE FROM CONTINUOUSLY EXTRUDEDFILMENTS PRODUCED BY A WET SPINNING PROCESS WHEREIN THE WEB CONSISTSESSENTIALLY OF ALTERNATELY ARRANGED CONTINUOUS FILAMENTS OF RELATIVELYLINEAR PORTIONS (A) WHICH ARE PHYSICALLY CROSS-LINKED TO EACH OTHERWITHOUT THE USE OF BONDED AGENTS AT VARIOUS PORTIONS ALONG THE LENGTH OFSAID FILAMENTS TO FORM A LATTICEWORK STRUCTURE SAID FILAMENTS ALSO HAVEFINELY FOLDED PORTION (B) WHEREIN THE FINELY FOLDED PORTIONS ARE EVENLYDISTRIBUTED OVER THE ENTIRE AREA OF THE WEB THE WEB HAVING REGULARLYARRANGED PROJECTIONS AND PERFORATIONS SUCH THAT THE FILAMENT PORTIONS(A) AND (B) ARE ENTANGLED WITH EACH OTHER AT EACH OF THE PROJECTIONS TOFIX AND REINFORCE THE LATTICEWORK STRUCTURE, THE WEB HAVING ANARRANGEMENT SUCH THAT THE WEB REPRESENTS AN INFINITE NUMBER OFPROJECTION DISTRIBUTED GEOMETRICALLY OVER THE WHOLE SURFACE OF THE WEBAND THE FILAMENTS BEING UNITED WITH EACH OTHER AT THESE PROJECTIONS. 2.The web according to claim 1 wherein the projections and perforationsare alternately arranged in the lengthwise and laterwise directions ofthe web.